Catalytic hydroforming process



Filed Janf, 1966 H. P. HEBERT ET AL CATALYTIC HYDROFORMING PROCESS ai v. ||5o |200 |250 CATALYST CALC|N|NG TEMP. (F.|

INVENTORS HUGH P. HEBERT Y SEYMOUR C.S UMAN IIOO ATTQRNEY United States Patent O 3,336,218 CATALYTIC HYDROFORMING PROCESS Hugh P. Hebert, Princeton, and Seymour C. Schuman,

Rocky Hill, NJ., assignors to Cities Service Oil Company, Bartlesville, Okla., a corporation of Delaware Filed Jan. 3, 1966, Ser. No. 518,271 3 Claims. (Cl. 208-136) The present invention -relates to catalytic hydroforming f liquid hydrocarbon fractions. More particularly, the invention enables improvements in catalytic hydroforming processes by employing a supported cobalt oxidemolybdenum oxide catalyst prepared in la critical manner.

The term catalytic hydroforming as used herein refers to processes of the type wherein a hydrocarbon fraction is subjected to treatment at high temperature and superatmospheric pressure in the presence of hydrogen gas and a suitable catalyst to provide a highly aromatized or otherwise chemically reconstructed product. The hydocarbon feedstock t0 the hydroforming process is preferably one boiling in the gasoline range, e.g. naphtha, whereby the product has a higher octane number. Thus, the term catalytic hydroforming connotes something more than mere purification of a hydrocarbon fraction, such as desulfurization. Accordingly, among the hydrocarbon conversion reactions which may occur to a greater or ylesser extent during the hydroforming process are dehydrogenation of naphthenes, to aromatics, hydrocracking of higher boiling parafiins, isomerization of paraflins to products having a greater degree of chain branching, cyclization, and desulfurization.

It is known to employ catayst compositions of molybdenum oxide on a suitable support material, such as alumina, in the hydroforming of gasolene boiling range fractions. Further, it is known to employ supported cobalt oxide-molybdenum oxide catalysts to effect purification of hydrocarbon fractions, for example, hydrodesulfurization.

The present invention is predicated on the discovery that a supported cobalt oxide-molybdenum oxide composition prepared in a critical manner functions as a highly effective hydroforming catalyst. More particularly, the cobalt oxide-molybdenum oxide catalyst utilized in the practice of the present invention has a high activity, excellent stability and enables exceptionally outstanding yields of liquid hydrocarbon product containing at least 6 carbon atoms (C6| hydrocarbons) when reforming to a given octane level. Accordingly, the hydroforming process of the invention provides substantial economies by enabling the hydrocarbon feedstock to be hydroformed to a higher octane number at a -given feed rate or at a higher feed rate at a given octane number.

The above and other advantages of the invention are obtained by subjecting a liquid hydrocarbon fraction to lhydroforming conditions in the presence of a catalyst calcined at a temperature of 1375 F. to. 1425 F. and consisting essentially of cobalt oxide and molybdenum oxide upon on alumina support.

The catalyst compositions contemplated by the present invention may be formed by a variety of methods. One suitable method, for example, involves impregnating a particulate absorbent alumina gel, which is preferably -gamma-alumina, with solutions of cobaltous and molybdenum salts, and subsequently calcining the composition at a temperature of 1375 to 1425 F. The catalyst composition may also be prepared, for example, by coprecipitating alumina, M003 and C00, followed by calcining the composition at the above-noted temperature.

The Weight ratio of C00 to M003 in the catalyst composition is preferably within the range of about 0.2 to about 0.4, While the sum of the weights of C00 and M003 is from 6% to 20% of the total Weight of composition. Catalysts containing the stated amounts of C00 and M003 have significantly higher activity compared to a standard alumina-supported molybdenum oxide hydroforming catalyst. As used herein, catalyst activity is defined as the ratio 0f feedstock space velocity (weight 0f feed per hour per Weight of catalyst) enabled lby the COO-M003 hydroforming catalyst of this invention to the space velocity enabled by a standard 11% molbdenum oxide on alumina catalyst at a constant hydroforming temperature and product octane level. The higher activity catalysts utilized in the present hydroforming process enable significantly higher feedstock throughputs when hydroforming to a given octane number.

The sum of the weights of C00 and M003 in the catalyst composition also inuence the activity ofthe catalyst composition. Accordingly, catalysts containing a total of at least 6% of cobalt oxide and molybdenum oxide have outstanding activity, although higher metal contents provide even higher activity. However, when the su-m of the cobalt oxide and molybdenum oxide contents 0f the catalyst exceeds 20% by weight, the stability 0f the catalyst is deleteriously affected. Thus, regeneration of the catalyst containing such high cobalt oxide and molybdenum oxide contents results in a serious decrease in catalyst surface area.

In general, C00:Mo03 weight ratios above the range indicated above increase the yield of undesirable methane from the hydroforming process, While decreasing the yield of desirable (36+ liquids, i.e. liquid hydrocarbons of at least 6 carbon atoms. y0n the other hand, Co0:Mo03 ratios below the indicated range also decrease Cg-I- liquid yield, while increasing the formation of undesirable coke products.

Catalyst having the best combination 0f activity, stability and Cg-lselectivity are those wherein the weight ratio is 0.27 to 0.29 and the sum of the weights of CoO and M003 is from 9% to 17% by Weight of the total Weight of the composition.

The temperature at which the lumina-cobalt oxidemolybdenum oxide catalyst composition is calcined is an essential feature of the present invention. Thus, we have found that COO-M003 catalysts calcined at a temperature within the range of l375 F. to 1425 F., and preferably from 1380 F. to 1420 F., enable unexpectedly superior yields of C64-hydrocarbons at a given octane level compared to COO-M003 catalyst compositions calcined at temperatures falling outside of this range, as well as conventional alumina-supported M003 hydroforming catalyst. The calcining of the catalyst composition may be advantageously effected in an oxidizing atmosphere, for instance air, for a period of at least one hour and preferably for 11/2 to v4 hours.

In Vpracticing thel hydroforming process of the present invention, a hydrocarbon fraction is contacted With the supported COO-M003 catalyst in the presence of from about 500 to about 8,000 s.c.f. of hydrogen per barrel of hydrocarbon feed at a temperature from about 700 F. to about 1,000 F., preferably from about 800 F. to 950 F., and at a pressure of from about 50 to about 1,000 p.s.i.g. preferably to 500 p.s.i.g. The space velocity at which the contacting is effected may advantageously vary from about 0.20 to about 2.0 Weight 0f liquid feed/hr./Weight of catalyst (w./hr./w.), although space velocities Within the range of 0.3 to 1.3 w/hr./w. are most preferred. The catalyst is preferably maintained in a fluidized state during contacting with the liquid hydrocarbon feed. For this purpose, the supported cobalt Oxidemolybdenum oxide catalyst is advisably employed in the form of microspheres having diameters of from about 20 to about 100 microns.

In addition to the advantages previously noted, the supported COO-M003 catalyst utilized in the present invention enables the hydroforming process to be carried out at relatively low pressures without significant increase in coke formation. The use of lower operating pressures, e.g. 100 to 300 p.s.i.g., results in further increases in the yield of CS-I-liquid hydrocarbons The preferred hydrocarbon feedstock employed in the hydroforming process is a hydrocarbon fraction boiling in the gasolene range, i.e. 185 F. to 450 F. For instance, the feedstock may be thermally or catalytically cracked naphtha, virgin naphtha, coker naphtha, Fischer-Tropsch naphtha, or mixtures thereof, with virgin naphtha being preferred. The present process is also useful, however, in dehydrogenating dicyclic naphthene feeds boiling within the range of 400 F. to 500 F., such as kerosene, to produce dicyclic aromatic hydrocarbons.

Regeneration of the catalyst composition may be suitably accomplished by combusting carbonaceous contaminants deposited thereon as a result of the hydroforming process. In accordance with one suitable regeneration procedure, the spent catalyst is contacted with air at a temperature of 1,000 F. to 1300 F., e.g. 1l25 F. It should be noted that the COO-M003 catalyst compositions utilized in the invention have improved stabilities compared to conventional molybdenum oxide on alumina hydroforming catalyst. The tendency of the molybdenum component to sublime upon regeneration is inhibited by the cobalt oxide and the activity of the catalyst is thus maintained for a relatively longer period of time.

The invention will now be further described with reference to the following example, which is presented solely for the purpose of illustration and should not be interpreted as limiting the invention.

In each of the runs of this illustration, a virgin naphtha feedstock showing the inspection set forth in table, below, was hydroformed by conventional uid bed techniques at a temperature of 870 F. and a pressure of 200 p.s.i.g. and at a space velocity of 0.7 in the presence of 2500 s.c.f. of hydrogen per barrel of liquid feed.

TABLE 1 Feedstock inspection API gravity 54.1 ASTM distillation IBP F-- 218 10% F-- 244 20% F 250 30% F 258 40% F 264 50% F-- 271 60% F 278 70% F 288 80% F 298 90% F 315 End point F-- 370 Recovery percent 98.0 Residue do 1.0 Dry point 332 K factor 11.80

For the purpose of control, a conventional catalyst composition of 11% M003 on a gamma-alumina support and calcined at a temperature of 1150 F. was employed as the hydroforming catalyst.

In each of the other runs, the catalyst employed was a composition of 13.2% M003; 3.67% C and 83.13% gamma-alumina. The COO-M003 catalysts differed only by the respective temperatures at which they were subjected to Calcining. In each case, Calcining was accomplished in the presence of air for two (2) hours.

The C64-selectivity of each of the alumina-supported COO-M003 catalysts was determined at constant octane level by the equation:

'C,+se1ecuvity=c,+vo1. percent yield from coo-Moo3 cat. minus C3+vol. percent yield from 11% M003 cat.

The Cs-l-selectivities of the COO-M003 catalysts are listed in Table 2, below, and are plotted versus their corresponding Calcining temperatures in the appended figure. In the figure, positive Cyl-selectivity values indicate improve C-i-liquid hydrocarbon yields compared to that obtained using the conventional 11% M003 on alumina catalyst composition at constant octane level, while negative Cyl-selectivity values indicate poorer yield.

TABLE 2 C-l-selectvtes of 13.2% M003; 3.67% COO; 83.13%'y- A1203 catalyst calcined at various temperatures Catalyst calcining temp. F.): Cyl-selectivity It will be noted that the catalyst Calcining temperatures utilized in the practice of the present invention, namely within the range of 1375 F. and 1425 F., provided unexpectedly superior hydroforming catalysts. Calcining temperatures falling just outside the stated range, i.e. 1360 F. and 1450 F., resulted in catalysts having poor C3+ selectivity compared to the control alumina-supported M003 composition.

It should also be noted that the COO-M003 catalyst calcined at a temperature of from 1375 F. to 1425 F. also possess excellent activities and stabilities. Thus, it was determined that at constant hydroforming temperatures and octane level, the catalyst utilized in the present invention would enable space velocities of from 1.65 to 1.92 times as great as the space velocity enabled by the control 11% M003 on alumina composition. Furthermore, high temperature aging tests conducted at 1228 F. for 30 days indicated that the surface area of the COO-M003 catalyst calcined at 1400 F. increased from 135 m.2/g. to 136 m.2/g., while the surface area of the M003 on alumina catalyst decreased from 370 m.2/g. to about 226 m.2/g.

While the invention has been described above in connection with certain preferred embodiments thereof it will be understood by those skilled in the art that various changes and modifications may be made without departing from the spirit and scope of the invention as expressed in the appended claims.

Therefore, we claim:

1. A hydroforming process which comprises subjecting a liquid hydrocarbon fraction boiling within the range of 185 F. to 450 F. to hydroforming conditions including a temperature between about 800 and 950 F., a pressure between about and 500 p.s.i.g. and a weight space velocity between about 0.2 and about 2.0 in the presence of between about 500 and about 8,000 standard cubic feet of hydrogen per barrel of hydrocarbon feed and a fluidized catalyst previously calcined at a temperature of 1375 to 1425 F., such catalyst consisting essentially of cobalt oxide and molybdenum oxide upon an alumina support.

2. The process of claim 1 in which the weight ratio of cobalt oxide to molybdenum oxide in said catalyst is' from about 0.2 to about 0.4, the sum of the weights of cobalt and molybdenum oxides is from 6 to 20 percent of the total Weight of the catalyst and the alumina support is gamma alumina.

3. 'The process of claim 2 in which the catalyst is calcined in an oxidizing atmosphere for a period of at least one hour.

6 References Cited UNITED STATES PATENTS 2,393,288 1/1946 Byrns 208-46 2,890,162 6/1959 Anderson et al 208-136 3,193,348 7/1965 Mooi 208-136 FOREIGN PATENTS 822,198 10/ 1959 Great Britain.

10 DELBERT E. GANTZ, Primary Examiner.

H. LEVINE, Assistant Examiner. 

1. A HYDROFORMING PROCESS WHICH COMPRISES SUBJECTING A LIQUID HYDROCARBON FRACTION BOILING WITHING THE RANGE OF 185* F. TO 450*F. TO HYDROFORMING CONDITIONS INCLUDING A TEMPERATURE BETWEEN ABOUT 800 TO 950*F., A PRESSURE BETWEEN ABOUT 100 AND 500 P.S.I.G. AND A WEIGHT SPACE VELOCITY BETWEEN ABOUT 0.2 AND ABOUT 2.0 IN THE PRESENCE OF BETWEEN ABOUT 500 AND ABOUT 8,000 STANDARD CUBIC FEET OF HYDROGEN PER BARREL OF HYDROCARBON FEED AND A FLUIDIZED CATALYST PREVIOUSLY CALCINED AT A TEMPARATURE OF 1375 TO 1425*F., SUCH CATALYST CONSISTING ESSENTIALLY OF COBALT OXIDE AND MOLYBDENUM OXIDE UPON AN ALUMINA SUPPORT. 